BOW-COMPASS

Bow″–com′pass (�), n.; pl. Bow-compasses (�). 1. 1. An arcograph.
2. 2. A small pair of compasses, one leg of which carries a pencil, or a pen, for drawing circles. Its legs are often connected by a bow-shaped spring, instead of by a joint.
3. 3. A pair of compasses, with a bow or arched plate riveted to one of the legs, and passing through the other.